Pilots are well aware...
...since air density relates directly to how much lift the plane gets from its airframe. When the weather gets hot you receive the lift that you would get from a higher elevation than you start at. You have to take it into account especially when you take off (if you want to make it over the fence at the end of the field). Back when I was studying it at the end of the 60s, it was called "density altitude", though it would not surprise me if they have another word for it now.
However, it is not something new nor something overlooked by scientists, as Johannes would have us believe.